Reaction Vessel Lid, 7-Nk, 250mL, Equivalent to Mettler Optimax Part # 51162699. Reaction Vessel Lid, 7-Nk, 250mL: 24/25 Outer CN, (2) 14/20 Outer SN, and (4) 19/22 Outer SN's, 88mm OD Flange; Equivalent to Mettler Optimax 1001 Part # 51162699. Mettler Optimax 1001 is a registered trademark of Mettler Toledo.